1. Field of the Invention
The present invention is related to a device for continuous folding of flat material such as signatures severed from a web of material in a folding apparatus assigned to a rotary printing press.
2. Background of the Invention
British Patent Publication No. 2 098 587 A discloses a signature transfer device in folder for a rotary printing press. Such a device includes a plurality of adjustable pressure rollers for holding down upper tapes to prevent the tapes from slipping on a signature while the signature is being transferred towards a position in which it will be folded on itself by a blade. Also, a mechanism is included acting on rollers for adjusting gaps between the upper tapes and the lower tapes to regulate the force with which the signature is sandwiched between the tapes in dependence of the number of pages or the thickness of the respective sheets. With these arrangements, the signature is prevented from getting wrinkled upon abutment against the front lays and from being skewed with respect to the blade when the signature arrives at the respective folding position.
U.S. Pat. No. 3,961,783 discloses an endless belt folder. In this configuration a folder apparatus includes an endless grooved belt mounted for movement along a linear folding path, opposite a second endless belt which is V-shaped in cross section. Said second endless belt interacts with the groove of the second belt thereby creating a fold in sheet material therebetween.
European Patent No. 0 434 987 B1, corresponding to U.S. Pat. No. 5,037,365, which hereby is incorporated by reference herein, discloses a folder with belt speed control. With this configuration a first longitudinally extending diverter means is disposed on a first side of the fold line and extends from the inlet section to the outlet section of said folder for deflecting sheet material projecting beyond an area on the first side of the fold line in a first direction as it moves from the inlet section to the outlet section of the folder. A second longitudinally extending diverter means is disposed on a second side of the fold line and extends from the inlet section to the outlet section of the folder, for deflecting sheet material projecting beyond an area on the second side of the fold line in the first direction as it moves from the inlet section to the outlet section of the respective folder. The first and second diverter means have diverter surfaces for gripping areas of the sheet material which increase as the sheet material moves away from the inlet section towards the outlet section of the folder.
A first arrangement of belts is provided at least partially disposed between said first and second diverter means gripping and moving sheet material along said first and second diverter means in a direction away from the inlet section towards the outlet section of the folder. Further, a second arrangement of belts at least partially is disposed between said first and second diverter means for gripping sheet material while it is being held and moved by the first arrangement of belts towards said outlet section of said folder. Consequently, said second arrangement of belts can grip and move the sheet material along the first and second arrangement away from the first arrangement of belts and towards the outlet section of said folder after said sheet material has separated from the first arrangement of belts.
Drive means are assigned to at least one of the belts of said first and second arrangement of belts for varying the running speed. A first signal generator means is provided for generating a first speed signal which is a function of the speed of said first arrangement of belts, a second signal generator means are provided to generate a second speed signal which is a function of the running speed of at least one belt in said second arrangement of belts. Finally a control means is provided for comparison of the first and second speed signals and for effecting operation of said drive means in order to vary the running speed of at least one of said belts in said arrangement of belts in response to a change in relationship between said first and second speed signal are provided.
In general, chopper folding means according to British Patent Publication No. 2 098 587 are speed limited in such a way that two are usually required to support one rotary printing press. Due to this requirement, auxiliary devices such as diverters or slow down sections or integrators also have to be added into the folder arrangement. Besides of being costly additions to the folder, these auxiliary devices also increase the risk of fold inaccuracies on their own inherent dynamic interactions with the signatures as they pass through each auxiliary section. Said belt assemblies according to U.S. Pat. No. 3,961,783 and European Patent No. 0 434 987 B1 are quite space consuming with respect to the placement of said folding arrangements.
In view of the drawbacks coming along with the above presented solutions according to the prior art and having sketched the difficulty generally encountered within the technical field it is accordingly one objective of the present invention to eliminate the need for chopper folding mechanisms.
A further alternate or additional object of the present invention is to eliminate the need for auxiliary equipment requirements.
A still further alternate or additional object of the present invention is particularly to eliminate the change in direction required to make a fold as necessary with chopper mechanisms.
According to the present invention, a device for continuous folding of flat material includes:
a driven rotating body arranged perpendicular to the conveying direction of flat articles,
said rotating body rotating about its rotation axis,
and surface sections assigned to the rotating bodies circumference tapered towards each other upon revolution of the respective cylinder.
The advantages according to the present invention reside in the facts that by driving a signature having one or more layers through the tapered surface portions of said folder rolls, a lineal fold is created, eliminating the change of direction required while stopping to make a fold as with well known chopper fold mechanisms. With the solution according to the present invention chopper fold mechanisms requiring numerous auxiliary equipment could be eliminated while creating a longitudinal fold upon the signatures being conveyed in conveying direction.
According to further advantageous embodiments according to the present invention said tapered surface sections, respectively, tapered towards each other at the same rate. Consequently the width of a V-shaped aperture between the surfaces arranged on the respective rotating body such as a cylinder narrows continuously upon revolution of said cylinder. Said tapered surface sections, respectively, form said V-shaped opening. The respective V-shaped opening""s width is dependent upon the angle of rotation of said tapered surface section. Thus, the degree of fold applied to the respective flat articles such as one-layered or multi-layered signatures is dependent on the respective angle of rotation of said surface sections arranged on said cylinder.
Said surface sections are arranged mirrored about a center mid point axis and form a respective three dimensional spiral, which advantageously is shaped as an Archimedean spiral to apply a longitudinal fold on the respective signatures. The configuration of said tapered surface sections arranged on the circumference of said cylinder form a folder roller.
Said folder roll is made of metal or plastic or a composite of these materials; other suitable materials are wood or a weldment construction.
The fold rollxe2x80x94having substantially spirally shapexe2x80x94may be made of a series of varying taper brushes said folder roll may have tapered surface sections made of guide portions arranged on the circumference of said cylinder.
Said cylinder has surface sections assigned thereto arranged so as to create a vertically upward directed longitudinally folded product. In a first configuration of the folder rolls said folder rolls have a mid portion in which the fold seam substantially is placed to create a longitudinal fold upon further rotation of said spiral, preferably an Archimedean spiral. The respective folder rolls may be arranged perpendicularly to the conveying direction of the flat articles. In a further advantageous embodiment, said folder rolls are oriented so as to create a horizontally extending fold on the left or right side, this may be chosen taken into account individual requirements of the respective print shop.
Said folder roll may be arranged to as to form a downward oriented fold in the respective signature so as to form a folded signature. Said folder roll including tapered surface sections arranged on a cylinder may comprise tapered surface sections terminating at each angle between 0xc2x0 and 360xc2x0 upon a complete revolution of said cylinder. Said tapered surface sections may have abutting portions to allow for an alignment of the signatures to be longitudinally folded.
To maintain the signatures in the centered recess during conveyance in conveying direction which upon further rotation of said folder rolls gradually narrows and to provide for a higher accuracy of the longitudinal fold, creaser means such as creaser belts, air nozzles, rotating knives or the like may be provided, assigned to the respective path of signature travel in conveying direction.
To provide for a higher effectiveness of the folding operation with said tapered surface sections assigned to said cylinder, said folder rolls may be arranged in the series configuration one arranged behind the other in inclined orientation to perform a horizontally extending path or below said signatures"" transporting path to provide for a longitudinally folded signature on the respective signatures spine.
The dynamic linear folding roll according to the present invention may be arranged in folder apparatuses either having retractable pin arrangements to seize the multi-layered signatures or in the alternative, said dynamic linear folding rolls may be provided in a pinless folder apparatus, at least one of said above mentioned folders being assigned to a web fed rotary printing press for commercial or newspaper printing.